Now I'm a Demon Lord! Happily Ever After with Monster Girls in My Dungeon (Manga) Volume 10 by Ryuyu

Nell’s in serious trouble! Which means it’s Demon Lord Yuki to the rescue!

While Yuki’s playing the heel and climbing the ranks of the demon world’s fighting tournament, Nell’s doing her best to recruit more demons against the devious fiends. Just when she and her comrades succeed in convincing one species, a mysterious group of villains attacks the tribe’s village! Treachery from without and within means their luck’s run out, and soon, she’s helping the survivors flee to safety. But when she realizes it’s only a matter of time before they’re cornered, Nell makes a courageous decision that may lead to her own end—if not for Yuki charging in as her dashing knight in shining armor! What’s on the horizon for these two?!

On top of that, Yuki finally meets the feared leader of the fiends for the first time! He challenges the ferocious man to a duel just as he’s about to clinch a top spot in the tournament. How will their encounter turn out?